1. Field of the Invention
The present invention relates generally to systems and methods for enhancing performance of lasers, and more particularly, for reducing power losses in laser beams internal to laser devices.
2. Description of the Related Art
There has been considerable recent interest in developing and improving the performance characteristics of lasers in general, and more specifically, gas lasers. Much of this interest has been prompted by the ever-growing acceptance of laser devices as everyday tools in the industrial workplace. Therefore, much of the attention to device improvement has centered on increased performance in terms of output power, power stability, reduced physical size, reduced cost and prolonged operational lifetime.
Particular efforts have been expended in the development of slab type gas lasers. These devices have one or more optical resonators each formed by a pair of optical mirrors that reflect a laser beam back and forth between each other. The laser beam originates in one or more discharge regions positioned between the optical mirrors. The devices are further characterized by their hybrid nature with the one or more discharge regions so shaped to be stable with a waveguiding influence on the laser beam in a first dimension and unstable with a freespace influence on the laser beam in a second dimension perpendicular to the first.
One performance robbing problem of waveguide lasers in general and slab lasers in particular is associated with non-discharge regions internal to the laser that are adjacent to the one or more discharge regions of the laser. In these non-discharge regions, the laser beam typically spreads out somewhat as it travels out of the waveguiding influence of a discharge region through the non-discharge region to a mirror and then back through the non-discharge region to the discharge region where it again experiences the waveguiding influence of the discharge region. In addition to non-discharge regions being positioned between a discharge region and an optical mirror element, conventional lasers also have non-discharge regions being positioned between two discharge regions when the conventional lasers have more than one discharge region.
As a result of traveling out of the waveguiding influence of the discharge region and back into the waveguiding influence of the same or another discharge region, the laser beam is not entirely coupled back into the discharge region. Since the laser beam is reflected back through the discharge and non-discharge regions many times before exiting the laser, a slight loss in coupling for a single transition between discharge and non-discharge regions results is significant cumulative losses. Unfortunately, in conventional lasers, the discharge regions must be kept far from the optical mirrors to avoid damage, thus, the non-discharge regions with their non-waveguiding influence tend to be significant in size.
Consequently, these non-discharge regions are typically associated with significant power loss due to the poor coupling of the optical radiation of the laser beams as they travel from the non-discharge regions back into the waveguides of the discharge regions. See, for example, D. R. Hall and C. A. Hill, xe2x80x9cRadiofrequency-Discharge-Excited CO2 Lasersxe2x80x9d, in Handbook of Molecular Lasers, edited by P. K. Cheo, Marcel Dekker, Inc., New York, N.Y., 1987, chapter 3, p.165-258, for a discussion of this phenomenon. A solution to this problem of laser beam power loss would be welcomed.
The present invention resides in a system and method for laser beam coupling. Aspects of the system and method involve a laser having first and second electrodes extending in a longitudinal direction and each having opposing first and second longitudinal ends. At least portions of the first and second electrodes are separated from each other in a separation direction transverse to the longitudinal direction by a separation distance associated with a Fresnel number of no more than 0.75. A gaseous lasing medium is disposed between the first and second electrodes at an operating pressure. The gaseous lasing medium is configured to form laser energy when excited by excitation energy from an energy source transmitted through the first and second electrodes.
Aspects further include first and second mirrors. The first mirror is positioned adjacent to the first longitudinal ends of the first and second electrodes and the second mirror is positioned adjacent to the second longitudinal ends of the first and second electrodes. The first and second mirrors have surfaces configured to form the laser energy into a laser beam that extends between the first and second mirrors. A plurality of electrical insulators comprise one or more solid materials.
Additional aspects include first and second waveguide extensions. The first waveguide extension is positioned at the first longitudinal ends of the first and second electrodes with at least one of the electrical insulators therebetween and extending in the longitudinal direction toward the first mirror. The second waveguide extension is positioned at the second longitudinal ends of the first and second electrodes with at least one of the electrical insulators therebetween and extending in the longitudinal direction toward the second mirror. The first and second waveguide extensions are electrically conducting.
Each of the first and second waveguide extensions have opposing surfaces separated from each other along the separation direction by substantially the separation distance. The electrical insulators are sized to prevent electrical discharge from occurring between the first electrode and the first waveguide extension, between the first electrode and the second waveguide extension, between the second electrode and the first waveguide extension, between the second electrode and the second waveguide extension, between the opposing surfaces of the first waveguide extension, and between the opposing surfaces of the second waveguide extension at the operating pressure of the gaseous lasing medium.
Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.